Louis D

22 hours ago, PeterC65 said:

I've set the focus control vertically so that I can more easily get to it at higher elevations.

I tend to leave my fine focus side pointed downward on both my 72ED and 90 APO.  That way, I'm generally coming in at it with my fingertips from underneath rather than the sides of my fingers from over top.  It looks like you might not have enough clearance with your mount at zenith to do this, though.

Enjoy that scope.  I had debated getting it as an upgrade to my 72ED (FPL-51 doublet), but decided to upgrade my aperture to 90mm at the same time.  The triplet part was just a bonus as one showed up used for a great price.  I did find out that 90mm triplets acclimate as slowly as 127 Maks and 8" Dobs though. 🙄

On 04/11/2019 at 13:08, Louis D said:

I've thought about trading up to the AT72ED II with FPL-53 glass and the R&P focuser.

Just a follow-up to myself.  I ended up getting a good deal on a used TS-Optics Photoline 90mm f6.6 Triplet FPL-53 APO for Christmas 2019.  It basically has no false color in focus, but out of focus images are tinged red and green on either side of best focus, so it's no reflector when it comes to color correction.  It is quite sharp at all powers, and the 2.5" R&P focuser has no slip issues at zenith even with heavy BV or 2" eyepiece and diagonal loads.  The fine focus is a bit spongy, so it's no Moonlight or FT focuser, but it's fine for visual observing.  I really like the camera angle adjuster at the end of the drawtube, so I can safely change the angle of the diagonal without changing the focuser knob orientation in the process.  Overall, it's a fun little scope to use once in a while.  I still prefer my 8" Dob for most observing, though.

You might check AliExpress for the Maxvision branding.  Some of the focal lengths are available direct from China.  There's also the Opticstar XL version which also has a few focal lengths available.

Not every zoom eyepiece has filter threads.  My Celestron Regal 8-24mm zoom does not as it was intended for spotting scope usage.  I'm guessing the Leica ASPH, Zeiss Vario, and Swarovski zooms don't either since all were intended for spotting scopes.

I would like to see someone commercialize Mel Bartel's ZipDob design.  A 13.2" f/3 Dob with a ~1000mm focal length that collapses into a sub-25 pound box via a few folds sounds great.  Of course, eyepieces that perform well at f/3 tend to be expensive.

12 hours ago, Alien 13 said:

There are compromises with a MAK but I dont see the narrow field of view one of them

It is if you want an all around scope that can go from wide fields to high power.  A fast/short f-ratio reflector with an extremely well figured primary and coma corrector can do both.  However, it will be bulkier than an equivalent aperture CAT unless a minimal truss design is employed.  It will still require some extension/assembly before use, so the CAT is more user friendly in that regard.  Again, compromises.  No one scope is good at everything.

CATs are compromise scopes by design.  To achieve a compact form factor, they necessarily have long focal lengths and large central obstructions relative to reflectors of similar aperture due to their folded optical path.  Of course, refractors have no obstruction at all.  Large central obstructions reduce contrast.

CATs also have the issue of having to use baffles to prevent light from going straight into the eyepiece bypassing the optics because the eyepiece is looking along the optical axis instead of at a 90 degree angle.  These baffles reduce the maximum true, unvignetted field of view in smaller CATs relative to their reflector and refractor equivalents.  This compounds the narrow field of view caused by the long focal length previously mentioned.  This is not an issue with 14" and larger CATs due to their large rear ports when using 2" eyepieces.

The long focal length is caused by their slow/long focal ratios.  This leads to making it difficult to achieve maximum exit pupil size for narrowband filter usage (think OIII nebula filters).  Thus, filtered nebula images can tend to be somewhat dim.

Maks don't scale well beyond 10" for amateurs (20" for professionals) because the meniscus corrector becomes quite large and heavy.  There's no way to reduce its bulk.  It's similar to why no refractor was ever made over 40".

SCTs have really thin correctors, so they do scale well up to about 16" to 20" for amateurs and 54" in a professional setting (at least as a Schmidt camera).

Cassegrains (classic, RC, DK, etc.) scale very well since they have no front corrector.  The Hubble ST is an RC Cassegrain, and it is 94.5" aperture.  Pretty much all professional observatory class telescopes are Cassegrains of one design or another.  The Cassegrain design places the focal point in a convenient location for instrumentation.  Typically, there are tertiary mirrors and relay optics to bring the image out to the side along the altitude axis so the instruments can simply ride along on the azimuth platform.  Derotators take care of image rotation during tracking.

Try reducing the exposure when taking images of bright stars.  This will reduce bloating and sharpen the image.

Check the leg extension locks on the tripod.  Several I've looked at had broken clamps.  You can live with a broken clamp as long as you never need to extend the lower leg section, but ask for a discount if it wasn't disclosed.

Belated welcome from another Texan.

I would recommend some sort of tarp or drop cloth to catch small parts if you drop them in thick grass.  I accidentally unscrewed a thumbscrew from an eyepiece holder all the way, and it slipped out of my fingers into the grass.  Not being ferrous, I couldn't find it with a powerful magnet.  I've never found it and replaced it with a American made, steel cap head screw.  These Asian made screws seem to be formed by die casting pot metal based on one I sheared off just by over tightening it with my fingers.

Do you have a garage or similar perhaps that you could leave it setup in on a dolly/trolley/wheely bars/scope buggy and wheel it out to the driveway to observe?

Someone on SGL recently converted a broken motorized mobility chair into a motorized scope buggy to make moving it even easier.  If you're handy with wood, a non-motorized version isn't too hard to put together.

3 hours ago, Deepblue12 said:

Must admit mount was on loose stones…first time ever with a telescope so a lot to learn 😀

Put it on dirt/lawn to get decent dampening if you don't have any pads.

1 hour ago, Deepblue12 said:

Clarity seems good but with the 9mm a bit of image shake which i'm not sure where it came from.

Try putting some vibration suppression pads under each tripod foot to dampen the oscillations.

5 hours ago, Peter Drew said:

Astrosystems of Luton of which I was a founder director were the Vixen importers.  Rob Miller was responsible for the Vixen imports.  Opticron eventually took over the dealership following Rob's move to the USA. 

So, were you involved in the sheep and telescopes advertising campaign?  If so, what was that all about?

43 minutes ago, Zermelo said:

The Svbony red line or gold line should also work well.

I can vouch for the 20mm Redline working well in a 127 Mak:

The Orion is a poorer performing, but wider AFOV, SWA design for comparison.  f/12 is pretty forgiving on eyepieces.

Apparently, that bino accepts standard 1.25" eyepieces.  So, the SVBONY eyepiece would probably fit.  Whether it would come to focus would be an entirely different question.

I've never tried the 14mm ES82, but I do have the 12mm ES92.  The ES92 is nearly perfectly sharp and flat of field to the edge at f/6.  I would imagine it degrades slightly at f/5.

I have strong astigmatism in my observing eye, so I need to wear eyeglasses at the eyepiece.  The ES92s have just enough eye relief to comfortably take in the entire field of view with glasses on.  As far as I know, the ES82 series does not.

I've read multiple reports that the ES92 series is sharper than the ES82 series, though not quite as sharp as the TV Ethos and Nikon NAV-HW series.

It all depends on what you want or need from an eyepiece and what your budget is as far as deciding to which to buy.

That Meade green filter is so much brighter than my #58 green filter, and no wonder.  Look at the spectral response of the #58:

It peaks at just over 50% transmission in the 520nm range, and is much lower everywhere else.

It would be nice if someone made an interference filter passing the range from roughly 490nm to 630nm to filter out most of the poorly focused light in an achromat:

That Chroma green filter comes close if it was just a bit wider on the right side.

Here's the spectral response of the Meade green filter.  Despite not stacking it with the IR cut filter, it pretty effectively cut visible red:

By itself:

Stacked with IR cut:

I'm guessing my eye is not very sensitive to red light at 725nm and higher, but I can try stacking them sometime to see if there is a difference.  It would be nice if the green passband were shifted a bit further to the right like the Chroma version to better correspond to the eye's peak color sensitivity:

However, I only paid $30 for the set on clearance, not $1700 like the Chroma set; so I can't complain too loudly. 😁

3 hours ago, Jiggy 67 said:

You can imagine the scenario where an observer is concentrating on finding a target with a laser piercing the sky and then forgets whilst he walks away to change an eyepiece or something.

I use a momentary switch that has to be held down for the laser to stay lit.

3 hours ago, Jiggy 67 said:

You don’t always hear aircraft at high altitude nor is it in your mind whilst you are deciding what ep to select away from the scope.

A laser pointer on the ground seen at that altitude would appear about as bright as the full moon at most.  That, and the angle would not be conducive to entering the cockpit.  If it was at low elevation and the airplane on the horizon, the extinction of the beam would be even higher.

I was out tonight trying to use my QuikFinder because I didn't have a mount on my ST80 for a laser, just a QF mount.  OMG, what a pain just trying to sight in Venus!  I kept looking over my glasses while trying to stoop low enough and twist around enough to see up through the QF, making it nearly impossible to sight it in.  Not an issue with a laser finder.

I just got in a #12 Yellow and tested it out tonight on Venus, Saturn, Jupiter, and Luna in my ST80 (80mm, f/5).  I had my AT72ED mounted on the other side of my DSV-2B mount for comparison.  I used matching Celestron Regal 8-24mm zooms in each to speed up matching views.  I also tried a Minus Violet pale yellow filter that is lighter than a #8 Yellow, a Zhumell Moon & Sky Glow, and a Meade interference green filter intended for imaging.

My recollections:

Unfiltered: Saturn looks best.  Least affected by unfocused violet and red, needs all the light it can get due to dimness.  Luna has a distinct violet cast, but is otherwise decent.  Venus and Jupiter look terrible.  I could make out Venus's crescent shape, but it was blurred.  Jupiter had no banding visible.

Minus Violet: No effect on Saturn.  Luna gets a bit less violet and a bit more yellow, slightly improving sharpness.  Venus and Jupiter showed no improvement.

#12 Yellow: Darkens Saturn too much without improving anything. Luna gets noticeably sharper, but strongly yellowed.  Venus sharpens up nicely.  Jupiter looks better, but unfocused red now intrudes excessively, blurring bands and other fine details.

M&SG: Darkens image, does nothing to remove violet.  Nothing looked better with it.  Saturn is way too dark to observe.

#12 Yellow and M&SG: Cuts a bit of the yellow cast on everything, but noticeably darkens bright objects.  I'm not sure it improve sharpness or contrast on any target since it doesn't cut unfocused red.

Green Interference: Saturn is sharpest, almost matching the AT72ED.  Luna is sharp, but not much different from #12 Yellow.  Venus is very sharp, cutting through atmospheric dispersion of red and blue.  Jupiter is nearly as sharp as the AT72ED.  Belts and a tiny moon (Io?) just off the edge are clearly visible with no unfocused violet or red.  The high transmission of this filter in a broad green band is a good match for the achromat's characteristics.

Overall, though, the AT72ED stomped all over the ST80 despite giving up 8mm of aperture.  The ED scope wasn't perfectly color free since there was a bit of a red/green rim on Luna, but it didn't seem to affect sharpness much.  However, if you're willing to heavily filter bright objects, the ST80 can produce sharp images.  It also works fine on dimmer objects like Saturn without filtration.

20 minutes ago, JOC said:

Lasers are certainly not necessary and imo wouldn't find me stuff any quicker so why risk the hazrd of the laser?

See my post above yours.  Some older folks like myself simply can't twist their back and neck like they used to be able to due to injuries to either or both.

On 05/12/2021 at 03:43, Jiggy 67 said:

I don’t really get why you would need a laser.

I can't twist my back and neck around to use my Telrad and QuikFinder at altitudes above about 40 degrees anymore.  I can be on target in under a second with a laser.

It's pretty easy to scan the sky for blinking aircraft lights before turning on the laser.  You'd have to be near deaf to not hear a helicopter unless it was moving at a high rate of speed, which they rarely do.  I can hear them from inside my house with windows closed.  Also, resist the temptation to look for the exit beam at the front of the unit when the battery is low.  It can blind you in an instant if you get on axis with it.  All it takes is a bit of common sense to use lasers safely outdoors.

A bigger threat to aircraft this time of year are the Christmas laser projectors that miss the side of the house and shoot 100mW or higher powered beams into the air continuously.  All it takes is a passing storm or careless kid to knock them backward and aim them at the sky.

At the risk of restating the obvious, but because a few folks new to Pentax XWs don't realize it, the eye cup twists upward to position your eye at the correct distance from the eye lens.  As a result of not knowing this, they struggle with the long eye relief.

I thought I'd mention it just in case.